Hi everybody, Canadian here that just picked up a 2006 CB919 that has passed through a few different people. There's some weird stuff on it... but there is also a full Leo Vince titanium exhaust and a centre stand, so not too bad!

I really have only found two gremlins to exorcise, one being a really stiff clutch and a really sensitive throttle. The throttle one seems to be harder to deal with, if I can do anything about it at all - basically just is quite jerky going from on-throttle to off-throttle. I have had newer and older bikes, so I'm confident this is more than just normal drivetrain lash. Even if I just hit a bump in the road, it's enough to roll the throttle back a hair and it's almost like I took my hand off the throttle completely.

Any suggestions? I know this kind of snatchy throttle is endemic to early EFI bikes, so maybe it's a grin and bear it kind of thing

Do you have a true OEM setup or aftermarket?

Look at the clutch lever, take out the pivot pin and see if it's loose and if it has a bushing and is well lubed. I had to replace my cable, it's a bit of a trick, so let me know and I'll tell you how to do it the easy way.

So the lever is key, I've see after market without a bushing and it was a nightmare to use.

The throttle really shouldn't be any worse than most any other bike. I've learned to feather the throttle at lower RPM. The make an adjustable throttle that addresses this issue by making it longer (slower) pull at the start and back to regular after that. It's a cam in the twist.

I'd make sure your cable are well lubed and in good condition. I replaced my 2006 OEM clutch cable because it wasn't fully returning from each use. I had to flick it out with one finger. The new cable 'almost' fixed it, I can tell it's better, but needs more spring pressure down at the clutch.

Check that the throttle 'snaps' back without delay, it might just be an issue of doing a full lube. Cable lube (inside the cable housing) throttle tube clean and lube, clutch lever lube and check the pivot pin for a bushing and wear marks.

Also, do you have a PCIII computer for the EFI or is the bike stock?

I believe it does not have a PCIII. Throttle movement seems good, snaps shut okay

Following are the main three things that alone or combined makes the 919 throttle jerky.
#1
Too much cable slack, and assume any 919 never adjusted will have too much slack.
#2
Super mush front springs that in low gear rolloffs or snapoffs from low speed, will make the fork dive.
#3
Lousy mapping as can best be remedied by a PCIIIusb.

My experience was #1 was so obvious when I checked it, I did that first.
It helped, but did not at all cure it to an acceptable degree.
I found # 2 & 3 worked together to really make matters bad.
I sprung the bike for track day reasons primarily, and PC'd the bike as the mapping was horrid with stock cans or my Yoshi slipons.

Sprung, mapped and properly slacked has changed it from a on/off switch like bucking nightmare in slow crawly traffic that only clutch slippage could alleviate, to a rheostat like engine that I can walk down to below 1000 rpm in gear and never need to touch the clutch, even on a slight uphill grade with a passenger on.

I own and ride 5 motorcycles, all equipped with EFI. Of the group I'd have to say that my '07 919 which is completely stock has the best fuel mapping and throttle response. If you are having sensitivity issues, it's got to be that something is out of adjustment or somebody has messed with the EFI mapping. People always seem to think that the manufacturers are idiots and that they can do a much better job at engine management than the folks who engineered and developed the bike. That's often a wrong assumption.

The 919 has a sensitive throttle. Mcromo is right. As long as nothing is out of wack a set of fork springs and a pc111usb will fix the twitchy throttle feel. The front springs are too soft and will act like pogo sticks. Big bumps used to cause me to unintentionally give the throttle a little twist off then on as my body moved.
A pc111usb will allow you to tune your bike. This also helped me smooth out my throttle response so it wasn't so on/off.
The 919 does like either on the gas or off. Some constant throttle input all the time or no throttle.
Also give it time. After a while you'll get used to the sensitive throttle and it won't feel so abrupt.

This really annoyed me when I first got my 919, I thought it was just because I'd never ridden a fuel injected bike before. I've pretty much got used to it and had forgotten all about it till your post.
The other annoyance was the clunky gearbox, have got used to that as well.
Now the only thing that annoys me is the suspension, I thought it was OK at first, but the more I ride it the more it bugs me.

https://www.motosport.com/g2-ergonom...ube-cam-system

They don't list one for the 919.

Theres a long shot chance that one of the previous owners have put in heavier clutch springs.

Ever since Fuel Injection has been used on motorcycles, riders have complained about abrupt throttles. Aftermarket companies have made all sorts of money with fixes. My current bike is even more responsive than the 919 that I had. I like it that way.

On the flip side, there is a company that makes what they call a Petal Commander. It is inserted into the wiring that goes from the gas petal to the the ECU of a car or pick-up. It multiplies the input, giving the illusion that your vehicle now magically has more power. Costs $300. Guys on the truck forums think it's the greatest invention since tits.

Here's another brand, I think a few people on this forum use the motionpro.

https://www.motionpro.com/c/rev2-throttle

Hmmm, I wonder if the bale (twist tube) of a F4i or perhaps a CBR600 series bike might offer some advantage and be directly fittable into the control pod of the 919.
Like eons ago re a CB1100F bale being retrofitted into a SOHC CB750.

Also.
It's not just the bale, which can be constant diameter or cam shaped.
It's also the shaping of the slave on the throttle blade shaft.
I noticed our mid 2000s GSXRs have very cammed shaped slaves, to give much finer control at the smaller throttle opening re cracking the throttle back open re track riding, while also providing a faster throttle blade opening rate when larger throttle openings are needed, like when getting back on the gas hard.

I got PCIII specifically to address this issue, and was really happy with the result.

I have exactly 1 PCIII for the Hooner left in stock and a huge backorder for more which they seem to be in no hurry to make...

If you want one you should jump on it.

Still keeping an eye on this thread. Some updates:

-Cleaned & lubed the clutch lever pivot and tried to lube the cable. Did not seem to lube well, it's either a tight fit inside or it's full of crap. It did improve though... seems like new cables are pretty cheap, may replace it still.

-Throttle free play seems about dead on, cables seem good... generally everything seems ship shape in this department.

-I checked sag & preload... I did increase preload a hair in the front but generally everything seemed pretty good here too. I'm pretty light so if a bike is sprung too soft for me then the bike was designed wrong! (but again, seems ok)

-PCIII sounds like it could help, but I don't know if this is a $400 problem for me right now. Also I'm less sure this is a full exhaust... did Leo Vince make a full exhaust? It does seem like they made slip-ons (or bolt-ons, whatevs)

Test ride after freeing up the clutch and tweaking preload did not seem to make much difference to the throttle behaviour. I did realize that revs drop faster on a closed throttle than any other bike I've owned (maybe the Z1000SX was similar, but I was verrrrrry comfortable with the controls on that bike) so maybe I can adjust for that

I tried everything on my clutch cable/lever and just gave up and bought a new one. The new one made a little difference. Even with a new cable and lubed stock lever, it still doesn't go out all the way by itself very well.

I learned to feather the clutch to smooth out the throttle. I got used to it over the years. It probably wears out the clutch sooner, but that's not a big deal.

If you do replace the clutch cable, follow this:

1. Undo both ends.
2. unthread the top part so that it's a pretty straight shot thru the intake area.
3. attach the bottom of the new cable set to the top of the old cable with wire (paper clip) wrapped tight.
4. cover the attachment area with some duct tape.
5. pull the old cable down and out while dragging the new cable thru.

1
A 919 clutch is a light lever easy to engage and modulate unit, so if yours isn't - something is wrong.
In addition to the other points already raised by others, check the cable routing, especially if the handlebars are non stock. If someone before has rerouted, it's very possible the rerouting is causing some or all of the problem.

2
Changing the adjuster will do nothing, as the spring rate will not be changed, and the only difference realized will be a slightly higher sitting front end.

I know the spring rate is not changed, I am not changing the preload in an attempt to correct it. What I meant by that is that since I am able to adjust sag to something I am happy with, without too much change to the adjuster, means the spring rate is probably in the right ballpark for my weight. Given the other things that have been changed on the bike, I'm not sure that it's using the original springs (but I would guess that it is, as people usually change springs to something significantly stiffer)

If you're happy with it, that's what matters most.
And rest assured that if someone before you did a spring change, they'd have gone to stiffer.
From what I have seen here on this site over the years, the lightest stiffer spring anyone has fitted is in the area of being at least 10% stiffer.
That said in terms of the stock dual rate wound vs. aftermarket linear wound.
(There are also aftermarket progressive wound springs, but few here have fitted them and I don't recollect ever having seen any ratings info posted.)

New clutch cable made a huge difference, this is definitely where it's supposed to be at now. Problem is, I barely made it a minute into the test ride and now my turn signals don't work (fuse is good) and the FI is flashing a code for the TPS sensor.

Guess pulling the new clutch cable through snagged something, despite me being quite careful? Or maybe this is a totally unrelated problem. One of the previous owners might have done something dirty to the wiring as it has a Speed Triple style headlight & LED signals in the rear. BLEAH!

Did you lift the tank and remove some coil wires? That's what I did on mine. Took off two coil wires (IIRC) and moved the tank out of the way. I'm thinking you pulled a wire.

Nothing looks disconnected under the tank. Unplugged & reconnected the TPS for good measure. Took the turn signal switch apart, cleaned & greased it (was gonna need to do this anyway as the action was poor), but doesn't make a difference.

Sigh... here comes the part I really don't want to do. Took the tail off and yeah, there's probably a problem here. Whoever wired up these LED turn signals should be in jail! (I couldn't remove the tail without disassembling the tail light because the dumbass hardwired his license plate light into the harness BEFORE the lighting pigtail) There is a very Chinese looking LED signal flasher that I guess I will check out first. Will have to solve the turn signal problem before looking at the FI, because for all I know the lighting problem could be causing it via some kind of electrical fault

I hate when people do that crap. I'd get them back to stock and test it that way. Just run some wires to some stock bulbs and get back to any stock controllers.

I remember years ago that LEDs required a special resistor or controller, maybe that's screwed something up.

Whew!

Everything works again, and the controls feel pretty sorted out. Now that I'm not fighting the clutch the throttle doesn't feel so bad, and I can see myself getting used to it. EFI problem did not come back after flasher was replaced, happy about that!

I just took this off of that last used 990 Super Duke that I bought.

As you can see, it says K400 on the end.

The OEM throttle on a SD goes from closed to open in aproximately 1.25 inches. With the Throttle tamer, that distance is now aprox 1.75 inches. +Half inch or +40%. That's a lot. I prefer the Hair Trigger feel of the stock KTM. That's what I'm used to.

REALLY easy to swap. The hardest part is getting the grip off, and back on. If you had a spare grip on the Throttle Tamer, it's a 5 minute job.

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Hmmm, this looks interesting.
A nice have for track days re cracking the throttle back on, plus faster butterfly opening rate at the upper range of % opening.
As long as no more total degrees of twist are required, that is.

Micro, I'll bet they make what you described.

But what I have isn't like that. It takes more travel to do the same amount of work. Besides, the one I have is linear, not progressive.

I think I found what I was hoping to find on their website.
They have a listing for the 919 slightly erroneously listed as CB900F/916 ('02 - '07).
G2 Street Tamer Throttle Tube
$80
I will contact them later and get precise info to make sure it's what I am hoping it really is: Same total degrees of turn/progressive/more degrees of turn needed in the 0-10% throttle opening range.

Overall, I didn't like the feel of that K400. Thank goodness that the previous owner saved ALL the stock parts. The Throttle Tamer I have, was nice down low. But it felt lazy out on the road, once the speeds picked up, and more power was asked for.

If you had one that was progressively more aggressive, that would be ideal.

I may buy am extra set of grips, and keep a grip "perminently" stuck on the Throttle Tamer. It takes 5 minutes to change. There are definitely times that it would be useful.

At $65, the Throttle Tamer is realitivly cheap. VERY nicely made. Ice to have options.

Thanks for the added commentary!